Electric switch.



PATENTED SEPT; 15

A. H. BABGOGK.

ELECTRIC SWITCH.

APPLICATION FILED MAR. 23, 1903.

N0 MODEL.

WITNESSES.-

UNITED STATES Patented September 15, 1903.

PATENT OFFICE.

ALLEN H. BABCOCK, OF OAKLAND, CALIFORNIA, ASSIGNOR TO STANLEY ELECTRIC MANUFACTURING COMPANY, OF PITTSFIELD, MASSACHU- SETTS, A CORPORATION OF NEW JERSEY.

ELECTRIC SWITCH.

SPECIFICATION forming part of Letters Patent No. 738,752, dated September 15, 1903.-

Application filed March 23, 1903.

To all whom it may concern.-

Be it known that I, ALLEN I-I. BABCOCK, a citizen of the United States, and a resident of Oakland, California, have invented certain new and useful Improvements in Electric Switches, of which the following is a specification.

My invention relates to starting direct-current motors or a direct-current generator as a motor, and is particularly applicable to starting rotary converters from the directcurrent end.

The object of my invention is to provide means for starting such machines with the use of fewer and simpler switches than has heretofore been possible, for enabling the machine to start with asinall amount of current, and for allowing the field-oircuit to be opened when necessary without danger to the insulation from inductive discharge.

Referring to the drawings, Figure l represents the switch and the diagrammatic representation of the connections therefor embodying my invention, and Fig. 2 is an end elevation of the switch-blade.

In Fig. 1, G is the armature, and II is the shunt-field, of a motor or rotary converter. The armature is connected on one side through switches I and J and through circuit-breaker K to the positive or negative bus and on the other side to the negative or positive bus. Switch I is a starting-switch of the ordinary type, which cuts out in closing a step-by-step starting resistance L. Switch J, in shunt to switch I, is the main positive switch.

K is an overloadcircuit breaker of any wellknown type.

Shunt field H is connected at one side to the negative armature-terminal and at the other to switch-blades D E, which are both pivoted at M, held together by spring N, and moved by means of handle 0 on D. Adapted to contact with arm D are the contacts A, B, and C. A is connected to a point between circuit-breaker K and switch I, C to a point between switch I and the positive armatureterminal, and B through resistance P to the negative field-terminal.

Serial No. 149,018. (No model.)

F is a contact adapted to contact with blade E and is connected to contact A.

The operation is as follows: When the motor or rotary is at rest, all the switches are in the position shown. To start, circuit-breaker K is closed, blade D is moved to contact A, blade E simultaneously engaging contact F, and switch I is closed far enough to close the circuit through resistance L. Under these conditions the field is fully excited, the ar1nature-circuit is closed through resistance L, and the rotary starts. Switch I is next slowly closed until all of resistance L is cut out and the rotary is at full speed. Switch J is then closed and switch I is opened. Blade D is now moved over to contact C. This does not open the field-circuit, for blade E is held by contact F until blade D reaches contact C. As blade D reaches this point it strikes heel Q of switch-blade E, forces E out of engagement with F, and permits spring N to draw E over to D. Field H is now connected to the positive armature-termin al between switch J and the armature.

The purpose of shifting the field connection from A to C is as follows: If circuit-breaker K should open because of overload or short circuit, it is preferable to open switch J before closing K in order that if the overload or short-circuit continues circuit-breaker K may not be held closed to the possible damage of the rotary, but if field II were connected to A opening-, switch J would open the fieldcircuit, which is undesirable. If field II is connected to C, this difficultyidoes not exist.

The intermediate contact B and resistance P are provided in case it is necessaryto open the fieldcircuit by moving blade D from contact C while the field is excited. Contact B is placed near enough to contact C to allow here shown, since changes therein which do not depart from the spirit of my invention will be obvious to those skilled in the art.

I claim as new and desire to secure by these Letters Patent 1. In a starting device for dynamo-electric machines, a field-switch having one position of the switch-blade for starting, a second position for running, and a third position for discharging the field circuit, and contacts adapted to engage the switch-blade in each of said positions.

2. In a starting device for dynamo-electric machines, a field-switch having one position of the switch-blade for starting, a second position for running, and a third and intermediate positionfor discharging the field-circuit, and contacts :adapted to engage the switchblade in each of said positions.

3. In a starting device for dynamo-electric machines, a fieldswitch comprising two switch-blades normally held together by a spring, three contacts adapted to be successively engaged by one switch-blade in passing from starting to running position, and a fourth contact adapted to engage and retain the second switch-blade until the first switchblade has passed from starting to running position.

4. In a starting device for dynamo-electric machines, a fieldswitch comprising two switchblades normally held together by a spring, a contact adapted to engage one of said switch-blades in its starting position, a second contact adapted to engage said switchblade in its running position, a third contact adapted to engage said blade on opening the field-circuit, and a fourth contact adapted to engage and retain the second switch-blade while the first switch-blade is passing from starting to running position.

5. In a starting device for dynamo-electric machines, a starting-switch for the armaturecircuit, a field-switch, two blades therein normallyheld together by a spring and electrically connected to one field-terminal, a contact therein connected througha resistance to the other field-terminal, a second contact connected to a point between the armature and the starting-switch, a third contact connected to a point between the starting-switch and the line, and a fourth contact connected to the third-named contact and adapted to engage and retain one switch-blade While the other switch-blade moves from the third-named to the second-named contact.

6. The combination with a dynamo-electric machine of a startingrheostat therefor, a resistance connected to the field-windings of the said machine, a switch member connected to said field-windings, and three sets of contacts adapted to be successively engaged by said member, two of said sets being connected to the main circuit at opposite sides of said starting resistance and the other of said sets being connected to the said field resistance.

7. The combination With a dynamo-electric machine of a starting-rheostat therefor, a resistance connected to the field-windings of the said machine, a switch member connected to said field-windin gs, and three sets of contacts adapted to be successively engaged by said member, two of said sets being connected to the main circuit at opposite sides of said starting resistance and the other of said sets being connected to the said field resistance, and being placed intermediate to the first two sets.

8. The combination with a dynamo-electric machine, of a starting-rheostat therefor, are sistance connected to the field-windin gs of the said machine, a switch member connected to said field-windings, and three sets of contacts adapted to be successively engaged by said member, two of said sets being connected to the main circuit at opposite sides of said starting resistance and the other of said sets being connected to the said field resistance, and be ing so placed as to contact with the said switch member before the switch member breaks contact with one of the two first-named sets of contacts.

Signed at San Francisco, California, this 27th day of February, 1903.

ALLEN H. BABCOOK.

W'itnesses:

JNo. H. NOBLE, F. J. T. LEE. 

